1. Technical Field
The present disclosure relates to a sieve device, a supply unit including the sieve device, a developing unit including the supply unit, an image forming apparatus including the developing unit, and a method of supplying toner particles.
2. Description of Related Art
Image forming apparatuses which form images by developing electrostatic latent images with toner are known. In particular, it is widely known that electrophotographic image forming apparatuses form images by developing electrostatic latent images into toner images with toner and transferring and fusing the toner images on paper. Such image forming apparatuses are generally equipped with a developing device that develops electrostatic latent images into toner images. JP-2003-131485-A describes a supply device that supplies toner to a developing device with a high degree of accuracy.
Recently, small-sized toners are widely used for the purpose of improving image quality. Sometimes toner contains coarse particles undesirably produced in its production process or due to the occurrence of weak aggregation under high-temperature and high-humidity conditions. If containing coarse particles, toner cannot develop an electrostatic latent image into a toner image with high accuracy.
JP-2006-23782-A describes a method of removing coarse particles from toner by means of sieving. In this method, coarse particles are removed by sieving toner with a filter vibrated by ultrasonic waves. However, there is a concern that the apertures of the filter are clogged with toner particles softened by frictional heat generated due to vibration of the filter, or another concern that the apertures of the filter are enlarged by stress caused by vibration of the filter.
JP-2009-90167-A describes a sieve device having a rotation shaft, a cylindrical sieve disposed coaxially with the rotation shaft, and rotary blades attached to the rotation shaft.
Further, this sieve device has a mechanism of transporting powder from inside to outside of the cylindrical sieve. Thus, the powder is sieved only by rotating the rotary blades without vibrating the sieve.
The mechanism of transporting powder from inside to outside of the cylindrical sieve requires a large space for collecting powders passed through the sieve. Therefore, this sieve device and an image forming apparatus equipped therewith get undesirably large in size.